Grass cutting lawn mowers, in particular rotary power mowers are commonly used for the maintenance and care of residential lawns. Rotary power mowers have a cowling for housing one or more rotating cutting blades with a lateral opening in the cowling for discharging grass clippings, leaves, twigs and debris at a substantial velocity. In determining the most effective means of collecting the discharged materials certain factors must be considered. First, the extremely high velocity imparted to the materials by the rotating blades presents a safety hazard as these materials are discharged from the cowling. Second, the discharging conduit must effectively deliver the grass clippings from the cowling to the catcher without clogging the discharge cowling. Additionally, the catcher must be shaped such that there are no pockets for trapping the clippings and reducing efficient flow of the clippings from the cutting area to the grass catcher.
Prior art grass catchers have taken a variety of forms. For example, many older grass catchers are open topped trays into which the clippings are sent. Often, however, the grass clippings are blown away from the open topped grass catcher by the action of wind or air currents created by the moving lawn mower blades. These open topped grass catchers also are difficult to empty neatly. Furthermore, ecologists have determined that it is extremely undesirable to have grass clippings, which may contain organic pollutants such as nitrogen based fertilizers, to be freely dispersed into the environment through wind action. Moreover, upon decomposing, the grass clippings will release the organic pollutants into the environment, thereby creating a potential hazard to animal life, as well as the possibility of ground water contamination.
Other prior art grass catchers define flexible bags that are attached to the discharging conduit of a power lawn mower. These flexible bags often are provided with either an internal or an external support to keep the bag substantially open, thus facilitating the flow of clippings into the grass catcher. Many such grass catchers are subject to rapid deterioration either due the decaying action of wet grass clippings adjacent the material bag or due to the various stresses created on the material by the supporting structure. Furthermore, the material from which the bags are made generally provides a poor air flow. Consequently, the grass clippings often accumulate near the mouth of the prior art grass catcher, thus preventing a complete filling of the bag.
Still other prior art grass catchers have been made from a heavy duty metallic mesh material. These structures have been fairly heavy and costly to manufacture. Furthermore, the metallic materials are particularly susceptible to deterioration when subjected to the moisture present in the grass clippings and the various fertilizing chemicals that may be used on a lawn. Thus, the prior art metallic mesh grass catchers must either be made from either an expensive grade of material that is not subject to decay or they require extensive maintenance to prevent such decay.
An extremely efficient prior art grass catcher is disclosed in U.S. Pat. No. 4,665,684 entitled "GRASS CATCHER WITH EFFICIENT AIR FLOW" which issued to the applicant herein on May 19, 1987. The grass catcher disclosed in U.S. Pat. No. 4,665,684 is a container of generally tapered cylindrical or frustum shape formed from a light weight but sturdy plastic material. The grass catcher is provided with a plurality of spaced apart apertures which extend therethrough to encourage a circulatory air flow. The spaced apart apertures enable a sufficient escape of air to avoid the random rebounding of the grass clippings within the grass catcher. As a result of this construction, some of the air which transports the grass clippings will be able to flow through virtually each aperture of the side wall of the grass catcher even when grass clippings are gravitationally deposited on the bottom of the grass catcher. This pattern of air flow through the side wall will achieve a circulatory air flow with an enhanced ability to transport the grass clippings to the far end of the grass catcher. This circulatory air flow is enhanced by the tapered or frustum shape of the grass catcher. The preferred air flow is further attained by forming the smaller end of the grass catcher, or the end thereof closer to the discharge conduit of the lawn mower, as a solid surface substantially free of apertures.
The grass catcher disclosed in U.S. Pat. No. 4,665,684 is easily opened to provide for convenient dumping of the clippings from the grass catcher after it has been completely filled. The grass catcher also includes metallic handles to facilitate the lifting and dumping of the filled grass catcher.
Although the grass catcher disclosed in U.S. Pat. No. 4,665,684 is extremely efficient the plurality of circular apertures provided in the walls thereof may have the effect of developing a turbulent boundary layer of air flow adjacent the walls of the grass catcher which could effect the quality of the desired circulatory air flow. Furthermore, to manufacture the grass catcher disclosed in U.S. Pat. No. 4,665,684 requires a substantial amount of machining time since it is necessary to individually drill each aperture.
Therefore, it is an object of the subject invention to provide a grass catcher having means for improving the cyclonic air flow therein.
It is a further object of the subject invention to reduce the manufacturing costs associated with machining a grass catcher having a plurality of apertures.
It is another object of the subject invention to provide a grass catcher having few metallic parts that are susceptible to deterioration.